Influence of particle shape and size distribution on coating mortar properties

Abstract

This paper investigates the influence of aggregates grading and shape in coating mortar performance, both fresh and hardened stages (mechanical properties and durability). Eight samples of mortar were prepared, using Portland cement type CP II-E-32 (corresponding to American cement: I (SM) ASTM - C 595), natural quartzous aggregate, crushed gneiss artificial aggregate, hydrated lime and water. It was analyzed the packaging of aggregates by determining their grading curves, unitary gravity and void ratio. Aggregates shape was analyzed through images obtained with a stereoscopic magnifying. Regarding coating mortar properties, mechanical properties and durability were analyzed as an aggregates shape function and its granulometric distribution through evaluation of consistency, fresh and hardened state density, air entrained content, water absorption by immersion and porosity, pull-off strength, compressive strength - fc, flexural strength - ft and elasticity modulus - Ed and assessing fissurability. In general, results showed that the particle size curve and the type of aggregate influence significantly the properties analyzed and should be considered during dosing process of coating Portland cement mortar specification, hence many standards to concrete may not be suitable for these composite parts.

Keywords

• Coating mortar
• Aggregate types
• Aggregates grading
• Aggregates shape effect
• Particle packing